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Proceedings Paper

Detection of a distance-dependent rate of quenching by frequency-domain fluorometry
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Paper Abstract

The effect of the collisional quenching on the fluorescence intensity decays has been studied by frequency-domain fluorometry. We used an efficient (CBr4) and/or inefficient (CCl4 quencher to quench the fluorescence of 1,2-benzanthracene (1,2-BA). The wide range of diffusion has been obtained by using propylene glycol at different temperatures (-40 degree(s)C to 40 degree(s)C). The measured intensity decays cannot be satisfactorily fitted either to the Smoluchowski or Collins-Kimball (RBC) model, except the case of inefficient quencher in the presence of high diffusion. In particular, we observed quenching in diffusionless conditions (-40 degree(s)C). To describe the collisional quenching of the fluorescence more correctly we propose a new model which includes a distance-dependent quenching rate (DDQ model). The DDQ simulations show that the local concentration of quencher surrounding the excited fluorophore cannot be approximated by using the RBC model, except in the case of high diffusion and low quenching rate. The DDQ model describes well all measured intensity decays of 1,2-benzanthracene in the presence of CBr4 and/or CCl4. Also, the DDQ model more correctly predicts the curvature of Stern-Volmer plots and activation energies obtained from the temperature dependent rate of quenching.

Paper Details

Date Published: 1 April 1992
PDF: 12 pages
Proc. SPIE 1640, Time-Resolved Laser Spectroscopy in Biochemistry III, (1 April 1992); doi: 10.1117/12.58200
Show Author Affiliations
Jozef Kusba, Univ. of Maryland School of Medicine (United States)
Ignacy Gryczynski, Univ. of Maryland School of Medicine (United States)
Henryk Szmacinski, Univ. of Maryland School of Medicine (United States)
Michael L. Johnson, Univ. of Virginia School of Medicine (United States)
Joseph R. Lakowicz, Univ. of Maryland School of Medicine (United States)


Published in SPIE Proceedings Vol. 1640:
Time-Resolved Laser Spectroscopy in Biochemistry III
Joseph R. Lakowicz, Editor(s)

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